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Do these users login locally, too? And if so, shall screen not be started in this case?
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Hauke LagingApr 17 '13 at 8:46

You need give a much better description of your problem! 1. you can tie users only to sessions, not windows. 2. Without recompiling screen, you cannot prevent a user from issuing commands.
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BananguinApr 17 '13 at 9:56